Technical guidance for fixture of four point bending tester

Technical guidance for fixture of four point bending testerTechnical guidance for fixture of four point bending tester

Four point bending tester fixture-GB30367-2025

The four point bending tester fixture specified in GB 30367-2025 is used for mechanical property testing of dental ceramic materials. Its design must comply with the technical requirements in the standard appendix to ensure the accuracy and repeatability of the test results.

According to this standard, the core parameters of the four point bending fixture are as follows:

Supporting roller rod diameter: 1.5 mm to 5 mm (± 0.2 mm), used to support the specimen;

The center span of the support roller rod (L) is 16.0 mm to 40.0 mm (± 0.5 mm), which can be adjusted according to the size of the sample;

Loading method: Adopting a 1/4 point loading structure, that is, two inner loading rollers are located at 1/4 of the total span (L) of the outer support rollers, so that the bending moment is evenly distributed in the middle 1/2 span area;

Loading roller rod diameter: the same as the supporting roller rod, ranging from 1.5 mm to 5 mm (± 0.2 mm);

Material requirements: The roller bar should be made of hard steel or other hard materials with a hardness greater than 40 HRC, with a smooth surface and a roughness Ra of less than 0.5 μ m;

Measurement accuracy: The center to center distance of the support roller rod needs to be measured to within 0.1 mm to ensure accurate loading position.

This fixture is suitable for universal mechanical testing machines, with a crosshead speed set at (1 ± 0.5) mm/min for testing, and can accurately determine the bending strength and fracture toughness of ceramic materials. Due to the uniform stress zone generated in the middle of the specimen by four point bending loading, it can more accurately reflect the properties of the material body and avoid the problem of stress concentration at the loading point during three-point bending.

The four point bending tester fixture specified in GB 30367-2025 is used for mechanical property testing of dental ceramic materials. Its design must comply with the technical requirements in the standard appendix to ensure the accuracy and repeatability of the test results.

According to this standard, the core parameters of the four point bending fixture are as follows:

Supporting roller rod diameter: 1.5 mm to 5 mm (± 0.2 mm), used to support the specimen;

The center span of the support roller rod (L) is 16.0 mm to 40.0 mm (± 0.5 mm), which can be adjusted according to the size of the sample;

Loading method: Adopting a 1/4 point loading structure, that is, two inner loading rollers are located at 1/4 of the total span (L) of the outer support rollers, so that the bending moment is evenly distributed in the middle 1/2 span area;

Loading roller rod diameter: the same as the supporting roller rod, ranging from 1.5 mm to 5 mm (± 0.2 mm);

Material requirements: The roller bar should be made of hard steel or other hard materials with a hardness greater than 40 HRC, with a smooth surface and a roughness Ra of less than 0.5 μ m;

Measurement accuracy: The center to center distance of the support roller rod needs to be measured to within 0.1 mm to ensure accurate loading position.

This fixture is suitable for universal mechanical testing machines, with a crosshead speed set at (1 ± 0.5) mm/min for testing, and can accurately determine the bending strength and fracture toughness of ceramic materials. Due to the uniform stress zone generated in the middle of the specimen by four point bending loading, it can more accurately reflect the properties of the material body and avoid the problem of stress concentration at the loading point during three-point bending.